django-reversion doesn't support that use-case, I'm afraid.
If you don't ever use the serialized data, I'd suggest uninstalling reversion and "taking over" the database table using a new model in your app that matches the reversion models. Override db_table on the model meta to match the reversion tables, fake an initial migration, and then edit the model to take out the fields you don't want, mirroring the changes to the database with a migration. The end result is you have a mini "reversion" app of your own with just the features you need.